Connective Tissues Flashcards
What is the main functions of Connective Tissues
1) It binds, supports and strengthens other body tissues.
- A major transport system of the body (blood is a connective tissue).
- A major site of stored energy reserves (fat or adipose tissue is a
connective tissue).
Features of Connective Tissues; LIKE epithelia
CT is supplied by nerves
– (Exception: cartilage)
Features of Connective Tissues; UNLIKE epithelia
CT is NOT found on body surfaces
– (Think of where bones, cartilage, blood are located…)
- CT can be highly vascular
– (Exceptions: cartilage which is avascular and tendons with very
little blood supply)
Connective tissue (CT) is composed of…?
EXTRACELLULAR MATRIX (ECM) and CELLS
(CT = ECM + Cells)
What is the ECM is composed of?
1)Ground Substance (GS) in association with
2) Protein Fibres (3 major types in different proportions)
(ECM= GS + Fibres)
The protein fibres of the ECM are secreted by …?
the cells in
the ECM/CT
The structure of the ECM largely dictates the connective
tissue qualities, what are two examples of this?
Cartilage: ECM is firm and rubbery
Bone: ECM hard and inflexible.
What is ground substance composed of?
Water
* Proteins (gelatin in jelly!)
* Polysaccharides (sugars-Glycosaminoglycans (GAGS or
mucopolysaccharides)
(GS = H 2 O + proteins+ polysaccharides)
(GAGS) Glycosaminoglycans joins with core proteins to form…?
proteoglycans
(Proteoglycans: Core Protein + Glycosaminoglycan (GAG))
What is another name for Glycosaminoglycans (GAGS) & what is its structure?
Other name “mucopolysaccharides”
– They are long unbranched polysaccharides”
What are 4 Sulphated Glycosaminoglycans (GAGS)?
- Dermatan sulphate
- Heparin sulphate
- Keratan sulphate
- Chondroitin sulphate
-These bind to core proteins to form proteoglycans
What are Non-Sulphated Glycosaminoglycans (GAGS)?
-Hyaluronic acid
Hyaluronic acid does not bind directly to core protein backbone but is joined to various proteoglycans
(no protein core)
The glycosaminoglycan hyaluronic acid is unusual in that it is not sulphated or covalently bound to a core protein.
Highly polar and attract water so collectively, the glycosaminoglycans trap water to make the ground
substance more jelly-like.
(GAGS) Hyaluronic acid application?
Hyaluronic Acid: viscous slippery substance binds cells together.
Lubricates joints and maintains shape of eyeball
Hyaluronidase: how is it produced and its function?
produced by white blood cells, sperm and some bacteria.
This makes ground substance more liquid so they
can move more easily in it or makes access to the
egg easier for sperm.
Chondroitin Sulphate application?
supports and provides the adhesive
features of cartilage, bone, skin, blood vessels
Keratan Sulphate application?
found in bone, cartilage, cornea of the eye
Dermatan Sulphate application?
found in skin, tendons, blood vessels,
heart valves
Abnormal Periorbital ECM and
thyroid disease (Exopthalmos) info?
Most common in younger women
* Goitre (swollen thyroid gland)
* Autoimmune over-activation of thyroid (goitre)
* Autoimmune action on fibroblasts in ECM of eye (exophthalmos)
The deposition of glycosaminoglycans and the influx of
water increase the orbital contents
Can you sometimes get abnormal ECM ground substance?
Yes
How many different types of connective tissue fibres are there in the extracellular matrix (ECM) & what are they?
3
Collagen Fibres
Reticular Fibres
Elastic Fibres
Collagen Fibres features?
(thick) Very strong but flexible to resist pulling forces
- Features vary in different tissues e.g. more water around
collagen in cartilage than in bone.
what percentage does collagen make up if your body? & is it the most abundant protein?
- Collagen 25% of your body and is most abundant
protein!
Where are collagen fibres commonly found in the body?
bone, cartilages, tendons and ligaments
* Parallel bundles
What is reticular fibre composed of?
Composed of collagen with coating of glycoprotein
* Collagen in fine bundles with coating of glycoprotein
(more protein than sugar)
Are reticular fibres made with fibroblast?
Yes
Features of reticular fibres?
Provide strength and support
* Form part of the basement membrane
* Thinner, branching - spreads through tissue.
Are elastic fibres thinner than collagen fibres?
Yes
Reticular fibres form networks in vessels through which tissues?
Form networks in vessels and through tissues especially
adipose tissue, nerve fibres, smooth muscle tissues
Features of elastic fibres?
Fibrous network
Can be stretched 150% without breaking
What protein does elastic fibres consist of?
Consist of the protein elastin surrounded by the
glycoprotein fibrillin to give more strength and stability
Where is elastic fibres most commonly found?
in skin, blood vessels and lung.
What is marfan syndrome?
A hereditary defect in elastic fibres usually
resulting from a dominant mutation in a gene on
chromosome 15, which codes for fibrillin.
Fibrillin is a large glycoprotein (350 kDa) that
contributes to a structural scaffold for elastin.
Body produces growth factor Transforming
Growth Factor beta(TGFb) – increases growth
because does not bind normally to fibrillin to
keep it inactive (theory)
Indivituals with marfan syndrome are usually…
tall, long limbed, and often with a chest deformity
(e.g. protruding or collapsed sternum). Normal life
span but need medical vigilance to control BP etc
They may have weakened heart valves and arterial
walls, which can be life threatening.
Occurs in about 1 in 20,000 live births.
What are the two Common Connective Tissue Cell Types?
Fibroblasts
Adipocytes (fat cells)
Where are the fibroblast CT cells found?
Widely distributed in
connective tissues;
migratory
what are the function of fibroblast CT cells ?
Secrete components of
the ECM (fibres and
ground substance)
Where are the adipocytes CT cells found?
Under skin and around
organs
what are the function of adipocytes CT cells ?
Store fat
(triglycerides)
What are the Other cells found in Solid CT?
Macrophages (Histiocytes)
Plasma Cells
Mast Cells
Leucocytes
Features of Macrophages (Histiocytes) cells found in solid CT?
Phagocytic cells comes in fixed and wandering forms in connective tissue.
Where are the fixed Macrophages (Histiocytes) found and called in CT?
Lung; Dust cells
Liver; Kupffer cells
Skin; langerhans cells
Where are the wandering Macrophages (Histiocytes) found in CT?
In infection/inflammation/injury sites.
Features of Plasma cells found in solid CT?
From B-Lymphocyte. These produce antibodies.
Where are the plasma cells found in CT?
many sites especially the gut, , lungs, salivary glands, lymph nodes, spleen, red bone marrow
Are plasma cells found in both yellow & red bone marrow in CT?
No- just red
Features of mast cells found in solid CT?
produce histamine that dilates vessels
Where are the mast cells found in CT?
alongside blood vessels
Features of leucocytes cells found in solid CT?
Are white blood cells. Eg. neutrophils, eosinphils
Where are the leucocytes cells found in CT?
Migrates out from blood
What are the 2 Classifications of Connective Tissue:
Embryonic or Mature
What are the 2 types of Embryonic classification of Connective Tissue?
Mesenchyme
(embryonic)
Mucous
Features of Mesenchyme
(embryonic)
Gives rise to all other connective tissues.
* Consists of connective tissue cells (mesenchymal cells) in a semi-fluid
ground substance containing reticular fibres
Features of Mucous
Mucous CT has widely scattered fibroblasts embedded in jelly-like
ground substance.
* Supports Umbilical cord of foetus.
a. Embryonic Connective Tissues
What are the 2 types of Mature CT ; Connective Tissue proper
Loose; fibres create loose open framework- areolar tissue, adipose tissue, reticular tissue
Dense; fibres densely packed- dense regular, dense irregular, elastic
What are the 2 types of Mature CT ; Fluid connective tissue
Blood; flows within cardiovascular system
Lymph; flows within lymphatic system
What are the 2 types of Mature CT ; Supporting connective tissue
Cartilage; solid rubbery matrix-hyaline cartilage, elastic cartliage, fibrous cartilage
Bone; solid crystalline matrix
What are sometimes called specialised CT’s
Fluid connective tissue & supporting connective tissue
Mature CT; Loose connective tissue- areolar connective tissue facts
Most common form of CT
Loose
(Many cells,
fewer fibres)
Features of areolar connective tissue
Three types of fibres are present
(collagen, reticular and elastic).
Widely distributed around almost every
structure. Like a “packing material”.
Strength, Elasticity, Support.
Features of adipose connective tissue
Adipocytes dominant.
Central triglyceride droplet.
Found with areolar connective tissue (incl. fibroblasts).
White adipose (energy storage) and Brown adipose (heat
production).
Insulation. Energy source. Temperature control
Reticular connective tissue
Reticular tissues are abundant in reticular fibers, whereas dense connective tissues are abundant in collagen fibers. In reticular tissue, reticular fibers are loosely packed and form a mesh-like structure.
reticular fibres are the most predominant fibrous constituent, serves as the supporting structure of the bone marrow, liver and lymphoid organs (spleen, lymph nodes, and tonsils).
Dense Regular Connective Tissue
(More fibres,
fewer cells)
Tendons (muscle to bone); Ligaments (bone to
bone); aponeuroses (muscle to muscle).
Regularly arranged collagen
e.g. tendons (pulling along the fibre axis).
Shiny white colour;
Collagen fibres are not a living tissue;
Slow healing
Attachment.
2. Dense Connective Tissue
Dense irregeular connective tissue
Dense irregular connective tissue has fibers that are not arranged in parallel bundles as in dense regular connective tissue. Dense irregular connective tissue consists of mostly collagen fibers. It has less ground substance than loose connective tissue.
Due to high portions of collagenous fibers, dense irregular connective tissue provides strength, making the skin resistant to tearing by stretching forces from different directions. Dense irregular connective tissue also makes up submucosa of the digestive tract, lymph nodes, and some types of fascia.
Dense elastic connective tissue
Dense connective tissue proper is composed of a higher density of fibers, which may be regular (with parallel fibers such as that of tendons and ligaments) or irregular (with multidirectional fibers such as that of the pericardium), or elastic (with significant embedded elastin such as that of arteries).
Dense elastic tissue contains elastin fibers in addition to collagen fibers, which allows the tissue to return to its original length after stretching. Dense elastic tissues give arterial walls the strength and the ability to regain original shape after stretching (dense CT figure).
Hyaline connective tissue
(Dense network
of collagen and
elastic fibres)
Abundant.
Relatively weak, resilient gel in which fibres are
present but not obvious.
e.g. anterior ends of ribs; respiratory cartilage –
i.e. nose, trachea, bronchi.
Nasal septum, ends of long bones.
Flexibility and movement.
3. Supporting CT: Cartilage
Hyaline Cartilage
Elastic cartalige connective tissue
Elastic cartilage has abundant elastic fibers in addition to collagen, making the matrix much more elastic than hyaline cartilage. Elastic cartilage supports structures subjected to frequent deformation, including the larynx, epiglottis, and external ear.
it supports parts of your body that need to bend and move to function. Elastic cartilage can bounce back to its original shape, even after a strong force. Your ear is made of elastic cartilage. It can bend and move without hurting you before returning to its usual shape
fibrous cartalige connective tissue
fibrocartilage, type of connective tissue that provides structural support for the musculoskeletal system. Fibrocartilage is very strong. It is found predominantly in the intervertebral disks of the spine and at the insertions of ligaments and tendons
Fibrocartilage is very strong. It is found predominantly in the intervertebral disks of the spine and at the insertions of ligaments and tendons. Its main function is to act as a cushion within joints, where it helps manage compression forces and reduces stress placed on joints
Bone or osseous tissue
Bones are organs composed of several connective tissue types,
including bone tissue (which is either compact or spongy (BM))
Compact bone
Outer layer of bone and forms the
shaft of long bones.
It is also known as cortical bone.
Composed of many rod-shaped
units known as either Osteons or
Haversian systems (see soon).
Spongy bone
Porous inner bone tissue that lies underneath compact bone.
Also known as Cancellous bone
Lacks osteons
Wikipedia
Bone compact
Compact contains osteons.
Stores calcium & phosphorous.
Protection & support
Bone spongy
Lacks osteons, stores triglycerides (yellow marrow) and produces
blood cells (red marrow).
4 types of cells found in bones
1- Osteogenic cells:
mesenchymal stem cells
that develop, starts to lay
down collagen; become
trapped and become
osteoblasts.
2- Osteoblasts: bone-
forming cells. Lay down
more collagen,
mineralization process
starts.
3- Osteocytes: mature bone cells derived from osteoblasts trapped within the
extracellular matrix. Maintain bone tissue. Involved in exchange of nutrients
and wastes. Have gap junctions.
(Bone CT=ECM (mineralised)+ cells)
4-Osteoclasts:
* Large,
* Multinucleated cells
* Formed from the fusion of blood
monocytes
* Break-down bone
The Structure of Osteons (Haversian Systems
The basic unit of compact bone is the osteon, with four parts:
1. Lamellae:
2. Lacunae:
3. Canaliculi:
4. Central (Haversian) canal
Osteons are aligned along lines of stress (e.g. long axis of bone
shaft).
Osteon Structure
- Lamellae:
concentric rings of mineral salts for hardness (e.g.
calcium phosphate and calcium hydroxide, which together
form hydroxyapatite) and collagen (for tensile strength).
Osteon Structure
- Lacunae:
small spaces between lamellae
that contain mature bone cells (osteocytes)
Osteon Structure
- Canaliculi:
“minute canals” (containing EC fluid and
minute osteocytic processes) that radiate from lacunae
and provide routes for oxygen, nutrients and waste.
Osteon Structure
4. Central (Haversian) canal:
blood, lymph and nerves
Osteoclasts reabsorb…
dead bone
Chondroblasts lay down…
hyaline
cartilage callus
Osteoblasts lay down ..
new bone
Osteoclasts remodel..
new bone
Blood CT
Consists of blood plasma (a liquid extracellular matrix)
and formed elements (red cells, white cells and platelets)
Erythrocytes transport …
oxygen & carbon dioxide
Leukocytes combat disease:
Neutrophils and monocytes (macrophages) are
phagocytic, engulfing bacteria.
ii. Basophils (mobile) and Mast cells (immature
circulate; mature are fixed in tissues), release
substances (e.g. histamine) that intensify the
inflammatory reaction.
iii. Eosinophils are effective against certain parasitic
worms and in acute allergic response .
iv. Lymphocytes are involved in the immune
response.
Platelets (from megakaryocytes in red marrow): clotting
what is AGGRECAN
(protein +chondrotion suplahte (GAGS) + kertatan sulpahte (GAGS) when associated with hyalourinc acid are improtant components of HYALINE cartalige (end of bones, ribs, nose, laranyx, & trachea etc.
